OK, OK, I guess it's a planet

So, this object that's about 1 1/2 times the size of Pluto has been found at the edge of our solar system. And the astronomers are all like, "Is is really a planet? or is it one of those non-planets." For decades, and even now, there have been astronomers who say, "Pluto is totally not a planet. It's too small and... um... it moves funny." But now: